1. Field of Invention:
This invention relates generally to corrosion-resistant doors, and more particularly to an integrated one-piece fiberglass-reinforced molded plastic door, and to a method of fabricating a door of this type.
Conventional doors, whether made of wood, metal, synthetic plastic, or combinations of these materials, function effectively under normal environmental conditions. However, such doors are usually incapable of withstanding the difficult atmospheric conditions which prevail in pulp and paper mills, municipal and industrial water and sewage treatment plants, petro-chemical refineries, food and drug processing plants and in other installations in which doors are subjected to abnormal environmental conditions. Under such conditions, the atmosphere may be highly corrosive or exceptionally humid, or in other respects possess deleterious properties.
Thus, in many food processing plants the atmosphere in some areas may be subject to high concentration of moisture. With a typical jointed door, this atmosphere may result in delamination, cracking and in other defects. In a chemical processing plant, the atmosphere may contain hydrochloric acid and other corrosive vapors to which the conventional door is not resistant. In medical and drug laboratories, it is essential that the doors be non-porous and without crevices or cracks that may collect microbes. Conventional doors do not satisfy this requirement.
In order to provide an atmospheric-resistant door capable of withstanding abnormal conditions, the Pitt U.S. Pat. No. 4,374,693 discloses a door structure which includes a rectangular frame to which fiberglass reinforced face plates are attached, sounddampening material being sandwiched between these plates.
A door structure of the Pitt type is superior to a conventional door in a corrosive or humid environment, but it is relatively difficult and costly to manufacture, for the components have to be assembled and joined together. Also of prior art interest are the Burnett U.S. Pat. Nos. 3,328,500 and 3,832,264, and the Prosinski U.S. Pat. No. 3,232,017.